Active cell sorting has been developed almost five decades ago (see Fulwyler M. J. “Electronic separation of biological cells by volume,” Science, Nov. 12, 1965; 150(3698):910-911). The fields of use for the active cell sorting have increased since the first publication. This increase has resulted in annual sales of cell separation/cell isolation products of $2.5 billion in 2014 (www.marketsandmarkets.com/PressRelease/cell-isolation.asp, downloaded on 25 Feb. 2015).
Modern fluorescence-activated cell sorters have a throughput of several 10,000 cells per second. However, these cell sorters are quite expensive (more than 200,000 US$ per device) and are not suited for the sorting of very small amounts of cell material (e.g. from patient biopsies or other primary cells). Furthermore, the size of objects to be sorted is limited. For example, different nozzles are required when sorting different cells or multicellular organisms.
Prior art cell microfluidic sorters use pneumatically operated valves, as is known from Abate A R, Agresti J J, Weitz D A. Microfluidic sorting with high-speed single-layer membrane valves. Applied physics letters. May 17, 2010; 96(20), Fu A Y, Spence C, Scherer A, Arnold F H, Quake S R. A microfabricated fluorescence-activated cell sorter. Nat Biotechnol. November 1999; 17(11):1109-1111, and Fu A Y, Chou H P, Spence C, Arnold F H, Quake S R. An integrated microfabricated cell sorter. Anal Chem. Jun. 1, 2002; 74(11):2451-2457.
The use of these pneumatically operated valves is quite expensive as the control units including macroscopic solenoid valves typically cost around 25,000 US$ (for example from Fluigent).